NOAA Technical Memorandum NMFS-SEFSC- 551

PROTECTED SPECIES AERIAL SURVEY DATA COLLECTION AND ANALYSIS IN 

WATERS UNDERLYING THE R-5306A AIRSPACE 

FINAL REPORT SUBMITTED TO U.S. MARINE CORPS, MCAS CHERRY POINT 

M. APRIL GOODMAN 

JOANNE BRAUN-MCNEILL 

ERIK DAVENPORT 

ALETA A. HOHN 

U. S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

Southeast Fisheries Science Center 

Beaufort Laboratory 

101 Pivers Island Road 

Beaufort, NC 28516 

January 2007 
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 NOAA Technical Memorandum NMFS-SEFSC- 551 

PROTECTED SPECIES AERIAL SURVEY DATA COLLECTION AND ANALYSIS IN 

WATERS UNDERLYING THE R-5306A AIRSPACE 

FINAL REPORT SUBMITTED TO U.S. MARINE CORPS, MCAS CHERRY POINT 

M. APRIL GOODMAN1

JOANNE BRAUN-MCNEILL1

ERIK DAVENPORT1

ALETA A. HOHN1

1

NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort 

Laboratory, 101 Pivers Island Rd, Beaufort, NC 28516 

U. S. DEPARTMENT OF COMMERCE 

Carlos M. Gutierrez, Secretary 

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION 

Conrad C. Lautenbacher, Jr., Administrator 

NATIONAL MARINE FISHERIES SERVCICE 

William T. Hogarth, Assistant Administrator for Fisheries 

January 2007 

This Technical Memorandum series is used for documentation and timely communication of preliminary results, 

interim reports, or similar special-purpose information. Although the memoranda are not subject to complete formal 

review, editorial control, or detailed editing, they are expected to reflect sound professional work. 
2

NOTICE

The National Marine Fisheries Service (NMFS) does not approve, recommend or endorse any proprietary 

product or material mentioned in this publication. No reference shall be made to NMFS, or to this 

publication furnished by NMFS, in any advertising or sales promotion which would indicate or imply that 

NMFS approves, recommends or endorses any proprietary product or proprietary material herein or which 

has as its purpose any intent to cause directly or indirectly the advertised product to be used or purchased 

because of NMFS publication. 

This report should be cited as follows: 

Goodman, M.A., J.B. McNeill, E. Davenport, and A.A. Hohn. 2007. Protected species aerial 

survey data collection and analysis in waters underlying the R-5306A Airspace: Final report 

submitted to U.S. Marine Corps, MCAS Cherry Point: NOAA Technical Memorandum NMFSSEFSC-551, 25 p. 

Copies of this report can be obtained from: 

M. April Goodman 

NOAA Fisheries 

101 Pivers Island Road 

Beaufort, NC 28516-9722 

April.goodman@noaa.gov 

National Technical Information Center 

5825 Port Royal Road 

Springfield, VA 22161 

(800) 553-6842 or 

(703) 605-6000 

http://www.ntis.gov/numbers.htm 

Photo credits: 

Larisa Avens1

, April Goodman1, Tom Ninke1, 

1

NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort 

Laboratory, 101 Pivers Island Rd, Beaufort, NC 28516 
3

Protected Species Aerial Survey Data Collection and Analysis in 

Waters Underlying the R-5306A Airspace 

Final Report Submitted to U.S. Marine Corps, MCAS Cherry Point 

Executive Summary 

To be in compliance with the Endangered Species Act and the Marine Mammal 

Protection Act, the United States Department of the Navy is required to assess the potential 

environmental impacts of conducting at-sea training operations on sea turtles and marine 

mammals. Limited recent and area-specific density data of sea turtles and dolphins exist for 

many of the Navy’s operations areas (OPAREAs), including the Marine Corps Air Station 

(MCAS) Cherry Point OPAREA, which encompasses portions of Core and Pamlico Sounds, 

North Carolina. 

Aerial surveys were conducted to document the seasonal distribution and estimated 

density of sea turtles and dolphins within Core Sound and portions of Pamlico Sound, and 

coastal waters extending one mile offshore. Sea Surface Temperature (SST) data for each survey 

were extracted from 1.4 km/pixel resolution Advanced Very High Resolution Radiometer remote 

images. A total of 92 turtles and 1,625 dolphins were sighted during 41 aerial surveys, 

conducted from July 2004 to April 2006. 

In the spring (March – May; 7.9°C to 21.7°C mean SST), the majority of turtles sighted 

were along the coast, mainly from the northern Core Banks northward to Cape Hatteras. By the 

summer (June – Aug.; 25.2°C to 30.8°C mean SST), turtles were fairly evenly dispersed along 

the entire survey range of the coast and Pamlico Sound, with only a few sightings in Core Sound. 

In the autumn (Sept. – Nov.; 9.6°C to 29.6°C mean SST), the majority of turtles sighted were 

along the coast and in eastern Pamlico Sound; however, fewer turtles were observed along the 

coast than in the summer. No turtles were seen during the winter surveys (Dec. – Feb.; 7.6°C to 

11.2°C mean SST). The estimated mean surface density of turtles was highest along the coast in 

the summer of 2005 (0.615 turtles/km2, SE = 0.220). In Core and Pamlico Sounds the highest 

mean surface density occurred during the autumn of 2005 (0.016 turtles/km2, SE = 0.009). The 

mean seasonal abundance estimates were always highest in the coastal region, except in the 

winter when turtles were not sighted in either region. For Pamlico Sound, surface densities were 

always greater in the eastern than western section. The range of mean temperatures at which 

turtles were sighted was 9.68°C to 30.82°C. The majority of turtles sighted were within water ≥

11°C. 

Dolphins were observed within estuarine waters and along the coast year-round; 

however, there were some general seasonal movements. In particular, during the summer 

sightings decreased along the coast and dolphins were distributed throughout Core and Pamlico 

Sounds, while in the winter the majority of dolphins were located along the coast and in 

southeastern Pamlico Sound. Although relative numbers changed seasonally between these 
4

areas, the estimated mean surface density of dolphins was highest along the coast in the spring of 

2006 (9.564 dolphins/km2, SE = 5.571). In Core and Pamlico Sounds the highest mean surface 

density occurred during the autumn of 2004 (0.192 dolphins/km2, SE = 0.066). The estimated 

mean surface density of dolphins was lowest along the coast in the summer of 2004 (0.461 

dolphins/km2, SE = 0.294). The estimated mean surface density of dolphins was lowest in Core 

and Pamlico Sounds in the summer of 2005 (0.024 dolphins/km2, SE = 0.011). In Pamlico 

Sound, estimated surface densities were greater in the eastern section except in the autumn. 

Dolphins were sighted throughout the entire range of mean SST (7.60°C to 30.82°C), with a 

tendency towards fewer dolphins sighted as water temperatures increased. 

Based on the findings of this study, sea turtles are most likely to be encountered within 

the OPAREAs when SST is ≥ 11°C. Since sea turtle distributions are generally limited by water 

temperature, knowing the SST of a given area is a useful predictor of sea turtle presence. Since 

dolphins were observed within estuarine waters year-round and throughout the entire range of 

mean SST’s, they likely could be encountered in the OPAREAs any time of the year. Although 

our findings indicated the greatest number of dolphins to be present in the winter and the least in 

the summer, their movements also may be related to other factors such as the availability of prey. 
5

Introduction 

To be in compliance with the Endangered Species Act and the Marine Mammal 

Protection Act, the United States Department of the Navy is required to assess the potential 

environmental impacts of conducting at-sea training operations to sea turtles and marine 

mammals. Marine Corps Air Station (MCAS) Cherry Point’s restricted airspace, R-5306A, 

encompasses portions of Core and Pamlico Sounds, and is used on a regular basis by the U.S. 

Marine Corps for training activities that involve the deployment of ordnance from aircraft at two 

operations areas (OPAREAs): the Piney Island Bombing Range (BT-11), and the Brant Island 

Shoal Bombing Target (BT-9) (Figure 1). Both sea turtles (Epperly et al., 1995a,b) and marine 

mammals (Read et al., 2003a,b; NMFS at NOAA Beaufort Lab, unpublished data) inhabit the 

estuarine waters of North Carolina and are likely to occur in the vicinity of these OPAREAs. 

Since 1988, National Marine Fisheries Service (NMFS) research has demonstrated the 

importance of North Carolina’s inshore waters as developmental habitat for neritic, juvenile 

loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp’s ridley (Lepidochelys kempii) 

sea turtles (Epperly et al., 1995a,b; NMFS at NOAA Beaufort Lab, unpublished data). Aerial 

surveys (Epperly et al., 1995b) and public sighting records (NMFS at NOAA Beaufort Lab, 

unpublished data) have documented the occurrence of sea turtles in R-5306A; some sightings 

were within the vicinity of bombing targets BT-9 and BT-11. Telemetry and biopsy surveys in 

Pamlico and Core Sounds (NMFS at NOAA Beaufort Lab, unpublished data), along with boatbased surveys of the Neuse River estuary (Gannon, 2003) and Pamlico Sound including BT-9 

and BT-11 ranges (Read et al., 2003b), have demonstrated these areas are frequently used by 

bottlenose dolphins (Tursiops truncatus) as well. 

The use of Core and Pamlico Sounds by sea turtles and dolphins changes seasonally. As 

water temperatures warm in the spring, sea turtles enter the sounds and distribute themselves 

throughout these estuarine waters during the summer. Cooling water temperatures in the fall 

result in the migration of turtles from the sounds to warmer coastal waters (Epperly et al., 1995a, 

b). Turtles are rarely encountered in water temperatures < 11oC (Epperly et al., 1995c; Coles and 

Musick, 2000; NMFS at NOAA Beaufort Lab, unpublished data). While bottlenose dolphins are 

known to reside in the estuarine waters of North Carolina year-round (Read et al., 2003b), little 

is known of their seasonal distribution. Although data are limited, it appears bottlenose dolphins 

are found primarily in the northern areas of Pamlico Sound in summer. In the winter, bottlenose 

dolphins are commonly found in the southern Pamlico Sound, particularly in the southern part of 

the Neuse River, including coastal areas of Cherry Point MCAS. However, it is hypothesized 

that during the coldest months, when water temperatures do not support populations of prey, 

dolphins move from the estuary to nearshore coastal areas that border Pamlico Sound, 

particularly south of Cape Hatteras (NMFS at NOAA Beaufort Lab, unpublished data). 

Verification of the seasonal use of Pamlico Sound by these protected species may provide a 

window when impacts of training activities would be minimal or negligible. If water 

temperature is a primary factor influencing the movements of turtles and dolphins into and out of 
6

the Sounds, documentation of the sea surface temperature at which sightings occur may allow for 

predicting those windows when operations are more or less likely to impact these species. 

The Cherry Point OPAREA lies within the developmental habitat for both sea turtles and 

dolphins, and training exercises at the two bombing ranges (BT-9 and BT-11) occur on a regular 

basis. However, previous aerial surveys such as those conducted by Epperly et al. (1995b) have 

been limited within the OPAREAs due to restricted access, so the use of R-5306A by these 

species is unknown. As a result of restricted access, estimates of impacts to these species from 

training operations would be based on insufficient data. Aerial surveys are the most feasible 

means to obtain this information since R-5306A is a large area that encompasses a complex 

intersection of water bodies and land masses. 

We were contracted by MCAS Cherry Point for assistance in achieving the following 

three specific objectives: 

1. Survey the waters of Core and Pamlico Sounds within R-5306A to document the 

seasonal distribution of sea turtles and marine mammals sighted; 

2. Provide relative numbers of animals sighted as an index of abundance that can be 

compared among seasons within the scope of this survey; and 

3. Provide observer training to MCAS Cherry Point personnel sufficient to allow these 

personnel to conduct pre-exercise range sweeps and post-exercise impact surveys for 

protected species. 

Methods 

Aerial Survey 

From July 2004 to April 2006 aerial surveys were conducted in a high-wing, twin-engine 

aircraft over portions of Core and Pamlico Sounds that lie within R-5306A and extend 

approximately one mile offshore of those limits (Figure 2). We used survey methods similar to 

Epperly et al. (1995b). Surveys consisted of either 15 or 16 east-west oriented transects, with the 

starting transect randomly selected to reduce bias (Cochran, 1977; Eberhardt et al., 1979). 

Transects were equi-distant from the starting transect, and spaced 4.5 km apart. We surveyed 

approximately 3.8% of the coastal area and 6.9% of Core and Pamlico Sounds during each flight. 

Surveys were conducted at an altitude of 147 m and a ground speed of 166-175 km/hr, using a 

Garmin GPSMap 295 to maintain position along each transect during a survey. It took 

approximately five hours to complete all transects. We scheduled flights so that mid-survey 

would occur as close to noon as possible. Although we attempted weekly surveys, flights were 

undertaken only when winds were less than 18 km/hr and wave height was less than 0.6 m, with 

no or few whitecaps (Beaufort Sea State ≤ 3). If conditions deteriorated after a survey began, we 

aborted the survey. Two observers positioned on opposite sides of the plane reported sea turtle 

and dolphin sightings to a data recorder, who logged in positional data and associated time with a 

hand-held Garmin GPS 12XL. The data recorder also noted sea state, glare, flight speed, 

altitude, change in weather, fishing activity, visibility, and turbidity throughout the flight. Due to 
7

the difficulty of distinguishing species at high altitudes, we did not identify turtles to species 

except in the case of leatherback turtle (Dermochelys coriacea) sightings. All dolphins sighted 

were assumed to be bottlenose dolphins since they are the only dolphin species inhabiting the 

area surveyed. Group size and direction of movement was also recorded for dolphins. The data 

recorder was always positioned on the same side of the plane as the observer with the least 

amount of experience sighting animals and reported sightings only when actively engaged in 

training an observer, or when it became apparent that the observer did not see an animal. A 

minimum of two training sessions were required before MCAS Cherry Point personnel were 

considered trained.

Distribution and Density Data 

All estimates of density are surface estimates, and therefore do not account for animals 

below the water’s surface. We derived density estimates using strip-transect methods. A 

number of assumptions should be considered when using the strip-transect method to analyze 

data: 1) transect lines are located randomly; 2) sighting conditions such as sun position and glare, 

sea state, weather, size of animals, and sightability differences within the 0.15-0.30 km strip do 

not effect the observers ability to sight animals, and all animals are sighted; 3) animals are only 

counted once during each survey; and 4) sightings are independent events (Burnham and 

Anderson, 1984). We conservatively chose a strip width of 0.15 km based on previous aerial 

surveys of Core and Pamlico Sounds (Epperly et al., 1995b). Densities were derived by season: 

Spring (March-May), Summer (June-August), Autumn (September-November) and Winter 

(December-February) and by geographic area: Coastal, Pamlico and Core Sounds, Western 

Pamlico Sound, and Eastern Pamlico Sound (Figure 2). 

We estimated the density of animals per km2 for each season and geographic 

area using the following equation: 

D = N / A 

where: 

D = Density of animals observed 

N = Number of animals observed 

A = Area surveyed (km2) 

Sea Surface Temperature Data 

Sea surface temperature (SST) data was recorded during surveys using a Cyclops 300 

independent infrared temperature sensor mounted onto the outside of the survey aircraft. We 

also extracted SST data after surveys from 1.4 km/pixel resolution Advanced Very High 

Resolution Radiometer (AVHRR) remote images collected by NOAA Polar Orbiting 

Environmental Satellites (NPOES) 15, 16, 17, and 18. Images were downloaded from the U.S. 

southeastern regional node of NOAA’s Comprehensive Large Array-data Stewardship System 

(CLASS) website (NOAA Satellite and Information Service, 1989). Only images taken in the 

daytime were used. Data extracted from the images were pixel temperature values from the 

same day and were geo-located with turtle and dolphin sightings. We digitally reconstructed 

geo-coordinates (latitude and longitude) along transects from beginning and end waypoints using 
8

Matlab Software (The Mathworks, Inc., 1994). Geo-coordinates were converted from 

reconstructed flight lines and those associated with turtle sightings to row and column pixel 

locations based on the Mercator projection of the images (1248 rows x 1160 columns) and the 

bounding box (Northwest corner, 36.8943  ̊N, 87.8404  ̊W, and Southeast corner, 72.7996  ̊W, 

22.5862  ̊N) of the remote images. Row and column pixel locations were used to index and 

extract SST data and removed SST pixels identified by NOAA's Coastwatch as missing data, 

land, or clouds (NOAA Satellite and Information Service, 1989). Minimum, maximum, and 

mean values of the remaining pixels were used to describe the SST observed among satellites 

along each survey transect and during dolphin and turtle sightings. The null hypothesis that 

observing sea turtles and marine mammals was independent of the mean SST of surveys was 

tested by performing a χ

2

 test. 

Results 

Due to inclement weather, the project timeframe, military training exercises, pilot 

availability, and a NOAA issued aviation safety stand-down, surveys were not evenly distributed 

seasonally among years. We surveyed 8 times in the spring, 13 times in the summer, 14 times in 

the autumn, and 6 times in the winter for a total of 41 surveys. A total of 92 turtles and 1,625 

dolphins were sighted. 

Seasonal Distribution and Sea Surface Temperature 

In the spring the majority of turtles were sighted along the coast, mainly from the 

northern Core Banks northward to Cape Hatteras (Figure 3). A couple of turtles were sighted 

just within the eastern Pamlico Sound and one was within the vicinity of BT-11. By the summer 

turtles were fairly evenly dispersed along the entire survey range of the coast and Pamlico 

Sound, with only a few sightings in Core Sound and the Pamlico and Neuse Rivers. The only 

leatherback turtle sighted was just south of Cape Hatteras. In the autumn, the majority of turtles 

sighted were along the coast and in eastern Pamlico Sound; however, fewer turtles were 

observed along the coast than in the summer. One turtle was seen in the Neuse River. The 

greatest number of turtles sighted within Core Sound occurred in autumn, with four individuals 

being seen. No turtles were seen in the entire study area during the winter surveys. 

Dolphins were distributed along the entire survey range of the coast and within eastern 

Pamlico Sound in the spring, with only a few animals sighted in Core Sound, the Pamlico and 

Neuse Rivers, and West Bay (Figure 4). By summer the number of observed dolphins along the 

coast had declined, but were relatively evenly distributed in Pamlico Sound and could still be 

found in the Pamlico and Neuse Rivers. A few groups were sighted just outside Bay River, 

within West Bay, and in Core Sound. By autumn dolphin sightings increased along the coast 

once again, and large groups of 10–50 individuals were seen in and around the Neuse and Bay 

Rivers. In the winter, the majority of dolphins were along the coast and just inside Pamlico 

Sound, with some small groups of 1-6 individuals found in the Neuse River and West Bay. 

 

We were able to use the temperature sensor during only nine surveys due to inclement 

weather and equipment malfunctions. Since a valid statistical analysis would not be possible 

using these, we present only the results of SST data collected from images obtained from NOAA 
9

Polar Orbiting Environmental Satellites (NPOES). SST data collected from the temperature 

sensor will be provided to MCAS Cherry Point separately. 

The minimum SST encountered along transects for all surveys was 5.53°C and the 

maximum was 32.83°C (Table 5). The minimum mean temperature for all transects was 7.60°C 

(SE= 0.10), and the maximum mean temperature was 30.82°C (SE= 0.21). SST values were not 

available for all days, due to heavy cloud cover. The range of mean temperatures at which 

turtles were sighted was 9.68°C to 30.82°C (Figure 5). The range of mean temperatures at which 

dolphins were sighted was 7.60°C to 30.82°C (Figure 6). We rejected our null hypothesis (p < 

0.05) of independence of turtle sightings and SST; turtles were found more often in warmer 

water. We could not do so with dolphin sightings; sightings were distributed across all 

temperatures, albeit with a tendency towards fewer dolphins sighted as water temperatures 

increased. 

Seasonal Density 

The estimated mean surface density of turtles was highest along the coast in the summer 

of 2005 (0.615 turtles/km2, SE = 0.220) (Table 1). In Core and Pamlico Sounds the highest mean 

surface density occurred during the autumn of 2005 (0.016 turtles/km2, SE = 0.009). The mean 

seasonal abundance estimates were always highest in the coastal region, except in the winter 

when turtles were not sighted in either region. For Pamlico Sound, surface densities were always 

greater in the eastern than western section (Table 2). 

The estimated mean surface density of dolphins was highest along the coast in the spring 

of 2006 (9.564 dolphins/km2, SE = 5.571) (Table 3). In Core and Pamlico Sounds the highest 

mean surface density occurred during the autumn of 2004 (0.192 dolphins/km2, SE = 0.066). 

The estimated mean surface density of dolphins was lowest along the coast in the summer of 

2004 (0.461 dolphins/km2, SE = 0.294). The estimated mean surface density of dolphins was 

lowest in Core and Pamlico Sounds in the summer of 2005 (0.024 dolphins/km2, SE = 0.011). In 

Pamlico Sound, estimated surface densities were greater in the eastern section except in the 

autumn (Table 4). 

Observer Training 

The following MCAS Cherry Point personnel received training to conduct pre-exercise 

range sweeps and post-exercise impact surveys for protected species: Robin Ferguson (8 Aug. 

2004, 9 July 2005), Bill Rogers (22 May 2005), Gary Haught (11 March 2006), Bobby Luna (27 

Aug. 2004, 21 Nov. 2005), Will Gainey (10 July 2004), and Lissa Grimes (24 June 2005). 

Discussion 

Seasonal Distribution and Sea Surface Temperature 

While we observed more sea turtles in coastal than in estuarine waters, they were present 

in Core and Pamlico Sounds at all times of the year except for winter, similar to observations 

reported by Epperly et al. (1995b). The absence of turtle sightings during winter surveys 
10

indicates their emigration from these waters as SST fell below their tolerance level. As 

poikilotherms, sea turtles distributions are generally limited by water temperature (Bell and 

Richardson, 1978). The majority of turtles we sighted were within water ≥ 11°C. This finding is 

similar to what Epperly et al. (1995c) observed during aerial surveys in North Carolina nearshore 

and offshore waters from Nov. 1991 – March 1992. Likewise, Coles and Musick (2000), who 

conducted aerial surveys off North Carolina from May 1991-September 1992, observed turtles 

only in water ≥ 13.3°C. Although we sighted one turtle when the mean SST was 9.68°C, it was 

observed in coastal waters where fine-scale water temperatures were likely greater than the mean 

SST. 

Dolphins were observed within estuarine waters and along the coast year-round; 

however, there were some general seasonal movements. Most notable were during the summer 

when sightings decreased along the coast, and dolphins were distributed throughout Core and 

Pamlico Sounds, and in the winter when the majority of the dolphins were located along the 

coast and the southeastern Pamlico Sound. These observations coincide with the hypothesis 

(Hohn, unpublished data) that dolphins migrate from the estuary to the nearshore coastal areas 

that border Pamlico Sound, particularly south of Cape Hatteras during the coldest months, when 

water temperatures do not support prey populations of fish. Dolphins were sighted throughout 

the entire range of mean SST (7.60°C to 30.82°C), indicating that these temperatures are within 

their thermal limits. 

Seasonal Density 

Our density estimates for turtles in Core and Pamlico Sounds appear lower than those 

found in Epperly et al. (1995b). They estimated surface density of turtles per survey to range 

from 0-.305 turtles/km2 in the Core Sound, and from 0-0.065 turtles/km2 in the southern Pamlico 

Sound, with the greatest densities from late spring through the summer. Our surface density 

estimates per survey for the Core and Pamlico Sounds were calculated together and range from 

0-0.054 turtles/km2. For comparison, the greatest number of turtles sighted in the Core and 

Pamlico Sounds occurred on 6 November 2005, with six turtles sighted in the Pamlico Sound 

(0.044 turtles/km2) and two sighted in Core Sound (0.171 turtles/km2). A statistical comparison 

between our results and those from Epperly et al. (1995b) is inappropriate to make because 

survey timeframe and the number of surveys conducted in the Core and Pamlico Sounds varied 

between studies. Also, they used clinometers to measure the distance of animals from the 

trackline, and although observers recorded their own sightings during the survey, they were not 

engaged in training other observers during the survey. 

 

Boat surveys conducted by Read et al. (2003a) during July 2000 estimated the density of 

dolphins in Pamlico Sound (excluding BT-9 and BT-11) to be 0.24 dolphins/km2. They also 

estimated the density of BT-9 and BT-11 to be 0.11 dolphins/km2, and 1.23 dolphins/km2 

respectively, based on boat surveys conducted from July 2002 through June 2003 (excluding 

April, May, Sept. and Jan.) (Read et al., 2003b). Gannon (2003) estimated the density of 

dolphins in Turnagain Bay to be 0.65 dolphins/km2, and 0.30 dolphins/km2 for South River 

based on boat surveys conducted from 1998-1999. (Both Turnagain Bay and South River are 

within the Neuse River estuary). These density estimates are much greater than what we found 

in western Pamlico Sound, the only area with which we can make a comparison. For example, 
11

our density estimates ranged from 0.027 dolphins/km2 in the winter, to 0.215 dolphins/km2 in the 

autumn. It is likely that these differences in density estimates are not an indication of a decrease 

in population density of dolphins, but might reflect a difference in survey methods. Both the 

Read et al. (2003a, b) and Gannon (2003) studies were boat-based surveys. Because aerial 

surveys are conducted at a greater speed than boat surveys, it is more likely an animal will be 

missed during the survey, resulting in an underestimating of density (Marsh and Sinclair, 1989). 

Therefore, the boat based density estimates of Read et al. (2003a, b) and Gannon (2003) may be 

more accurate than the uncorrected estimates derived from our aerial surveys. However, our 

surveys cover a broader area and allow for relative comparisons within that larger area. In 

addition, their surveys in small areas were not conducted during all months of the year. For 

these reasons, a direct comparison with their density estimates is not possible. 

Our estimates of density may have been affected by a number of different factors. Since 

we did not measure the distance of turtles and dolphins from the transect line, it is possible that 

some animals outside the 0.15 km survey strip were included in our analysis. Epperly et al. 

(1995a) found that 13% of the turtles sighted were outside the 0.15 survey strip. Using this 

estimate, 14 of the 92 turtles sighted may have been outside our survey strip. Also, although the 

spacing of transects (4.5km apart) is sufficient when surveying for sea turtles, it is not ideal when 

surveying for bottlenose dolphins since they can reach a maximum known speed of 20.5 km/hr 

(Rohr et al., 2002). However, given the size of our survey area, transects spaced farther apart 

would likely have compromised our ability to provide accurate estimates of density. Likewise, 

our use of the data recorder as an observer while training observers, and the high number of 

observers needing to be trained may have affected our ability to sight animals. There were no 

corrections for these factors in the density calculations. 

Finally, our density estimates represent the number of turtles and dolphins on the surface 

of the water and do not account for animals that are below the surface, and thus, undetectable. 

An adult, female bottlenose dolphin that was radio tagged and monitored by satellite-based 

receivers spent an average of 87.1% (SE= 0.6) of the time submerged, with a mean dive duration 

of 25.8 (SE=0.5) seconds (Mate et al., 1995). Therefore, given our flight speed of 166-175 

km/hr, it is reasonable to assume that surveys did not account for all dolphins because some 

would have been submerged, and, thus, undetectable. 

Using data collected by means of radio and acoustic telemetry from loggerhead turtles 

within the Chesapeake Bay, Byles (1988) estimated that turtles spend 5.3% of their time on the 

surface during the summer and fall months. Therefore, for every one turtle on the surface there 

are 18.9 turtles estimated to be below the surface. Recent work in Virginia by Mansfield (2006) 

suggests that the surfacing behavior of turtles varies with season. She found that the mean time 

turtles spent on the surface in the spring ranged from 9.9%-30.0%. Turtles with higher surfacing 

times were also tracked in deeper, cooler waters of the Bay mouth or Atlantic coastline. Nelson 

(1996) also observed seasonal variations in surfacing behavior among juvenile loggerheads 

tracked in Georgia, with turtles spending a greater percentage of their time (19.0%) at the surface 

in the spring compared to later in the season. Because the variability in sightability (surfacing 

behavior) of turtles depends upon season and geographic location, we did not incorporate their 

correction factor into our density estimates. Determining the surfacing behavior of turtles and 
12

dolphins inhabiting North Carolina estuarine and coastal waters would provide more accurate 

density estimates. 

Conclusion 

Based on the findings of this study, sea turtles are most likely to be encountered within 

the OPAREAs when SST is ≥ 11°C. Since sea turtles distributions are generally limited by 

water temperature, knowing the SST of a given area is a useful predictor of sea turtle presence. 

Since dolphins were observed within estuarine waters year-round and throughout the entire range 

of mean SST’s, they likely could be encountered in the OPAREAs any time of the year. 

Although our findings indicated the greatest number of dolphins to be present in the autumn and 

the least in the winter, their movements also may be related to other factors such as the 

availability of prey. 

 
13

Acknowledgments 

We would like to thank all of the aerial observers (Tanya Bean, Bud Daniels, Ron Clayton, 

Denene Blackwood, Lisa Goshe, Matthew Godfrey, Wendy Cluse, Robin Ferguson, Bill Rogers, 

Sue Huntsman, Carol Price, Jon Altman, Gary Haught, Craig TenBrink, Blake Price, Bobby 

Luna, Stacy Kubis, Will Gainey, Emma Jugovich, Julie Dyble, Lissa Grimes) and pilots (Jack 

Meagher, Curtis Hinkley, Gary Ambrose, Mark Honeycutt, Leland Gibbs, and Phil Platt) who 

made this project possible. Their patience when the weather wasn’t cooperating, willingness to 

survey on short notice and holidays, and the enthusiasm and good humor they brought to each 

survey was much appreciated. Thanks also to Eric Griffith for statistic advice, Barbie Byrd for 

GIS tips, Wayne Hoggard for advice on using the temperature probe, and Larisa Avens and 

Larry Hansen for reviewing this report. Also, we would like to extend our gratitude to the air 

traffic controllers at Cherry Point for providing us with weather updates during flights, and for 

making sure we were aware of what was going on in the airspace at all times. 
14

References 

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(Caretta caretta) nesting on Little Cumberland Island, Georgia. Florida Marine Research 

Publications 33: 20-24. 

Burnham, K. and D. Anderson. 1984. The need for distance data in transect counts. Journal of 

Wildlife Management 48: 1248-1254. 

Byles, R. A. 1988. The Behavior and Ecology of Sea Turtles in Virginia. Ph.D. 

 Dissertation. Virginia Institute of Marine Science, College of William and Mary, 

Gloucester Point, Virginia. 112 p.

Cochran, W. G. 1977. Sampling Techniques, 3rd ed. Wiley and Sons, New York, 428 p. 

Coles, C. C. and J. A. Musick. 2000. Satellite Sea Surface Temperature Analysis and 

Correlation with Sea Turtle Distribution off North Carolina. Copeia 2000: 551-554. 

Eberhardt, L. L., D. G. Chapman, and J. R. Gilbert. 1979. A review of marine mammal 

 census methods. Wildlife Monographs 63: 1-46. 

Epperly, S. P., J. Braun, and A. Veishlow. 1995a. Sea turtles in North Carolina. 

Conservation Biology 9: 384-394. 

Epperly, S. P., J. Braun, and A. J. Chester. 1995b. Aerial surveys for sea turtles in inshore 

waters. Fishery Bulletin 93: 254-261. 

Epperly, S. P., J. Braun, A. J. Chester, F. A Cross, J. V. Merriner, and P. A. Tester. 1995c. 

Winter distribution of sea turtles in the vicinity of Cape Hatteras and their interactions with 

the summer flounder trawl fishery. Bulletin of Marine Science 56: 547-568. 

Gannon, D. 2003. Behavioral ecology of an acoustically mediated predator-prey system: 

Bottlenose dolphins and sciaenid fishes. Ph.D. Dissertation, Duke University, Durham, 

North Carolina. 244 p. 

 

Mansfield, K. L. 2006. Sources of mortality, movements and behavior of sea turtles in Virginia. 

Ph.D. Dissertation. Virginia Institute of Marine Science, College of William and Mary, 

Gloucester Point, Virginia, 367 p. 

Marsh, H. and D. F. Sinclair. 1989. Correcting for visibility bias in strip transect aerial surveys of 

aquatic fauna. Journal of Wildlife Management 53: 1017-1024. 

Mate, B. R., K. A. Rossbach, S. L. Nieukirk, R. S. Wells, A. B. Irvine, M. D. Scott, and A. J. 

Read. 1995. Satellite-monitored movements and dive behavior of a bottle-nosed-dolphin 

(Tursiops truncates) in Tampa Bay, Florida. Marine Mammal Science 11: 452-463. 
15

The Mathworks, Inc.. 1994. The MathWorks – MATLAB and Simulink for Technical 

Computing. http://www.mathworks.com/. Last accessed 8 December 2006. 

Nelson, D. A. 1996. Subadult loggerhead sea turtle (Caretta caretta) behavior in St. 

Mary’s entrance channel, Georgia, USA. Ph.D. Dissertation, Virginia Institute of Marine 

Science, College of William and Mary, Gloucester Point, Virginia. 132 p.

NOAA Satellite and Information Service. 1989. NOAA’s Comprehensive Large Array-data 

Stewardship System. http://www.class.noaa.gov/nsaa/products/welcome. Last accessed 8 

December 2006. 

NOAA Satellite and Information Service. 1989. NOAA Coastwatch Central Operations 

Homepage. http://coastwatch.noaa.gov/cw_index.html. Last accessed 8 December 2006. 

Read, A., K. Urian, B. Wilson, and D. Waples. 2003a. Abundance of bottlenose dolphins in the 

bays, sounds, and estuaries of North Carolina. Marine Mammal Science 19: 59-73. 

Read, A., J. Maher, K. Urian, and D. Waples. 2003b. Monitoring bottlenose dolphin use of the 

Brant Island shoal bombing target (BT-9) and the Piney Island bombing range (BT-11). 

Final report to MCAS Cherry Point. Duke University Marine Laboratory, 135 Duke 

Marine Lab Road, Beaufort, North Carolina, 28516. 

Rohr, J. J., F. F. Fish, and J. W. Gilpatrick. 2002. Maximum swim speeds of captive and freeranging delphinids: Critical analysis of extraordinary performance. Marine Mammal 

Science 18: 1-19. 
16

Animals

Transects 

surveyed 

(km2 )

Density 

(km2 )

Mean 

Seasonal 

Density 

Estimate

SE Estimated turtles

Mean 

Seasonal 

Abundance 

Estimate

SE Animals

Transects 

surveyed 

(km2 )

Density 

(km2 )

Mean 

Seasonal 

Density 

Estimate

SE Estimated turtles

Mean 

Seasonal 

Abundance 

Estimate

SE

10 Jul 1 167.6 0.0060 13 0 5.76 0.0000 025 Jul 5 179.6 0.0278 62 0 5.76 0.0000 0

 8 Aug 0 174.4 0.0000 0 1 5.76 0.1736 24 19 Aug 2 167.4 0.0119 27 1 5.28 0.1894 26 27 Aug 1 180.4 0.0055 12 0 5.76 0.0000 0

 4 Sep 0 147.5 0.0000 0 0 5.28 0.0000 0

 3 Oct 0 150.8 0.0000 0 3 5.28 0.5682 79

10 Oct 0 149.6 0.0000 0 0 5.28 0.0000 024 Oct 0 153.1 0.0000 0 0 5.28 0.0000 029 Oct 0 145.3 0.0000 0 1 5.28 0.1894 26

 6 Nov 0 145.4 0.0000 0 0 5.28 0.0000 011 Nov 1 146.7 0.0068 15 0 5.28 0.0000 020 Nov 3 150.3 0.0200 44 0 5.28 0.0000 0

Winter 13 Feb 0 152.2 0.0000 0 0 5.28 0.0000 0

 6 Mar 0 168.2 0.0000 0 0 5.76 0.0000 0

 14 May 0 158.3 0.0000 0 6 5.28 1.1364 157 22 May 0 152.3 0.0000 0 0 5.28 0.0000 0 30 May 2 152.3 0.0131 29 2 5.28 0.3788 52

 4 Jun 0 151.8 0.0000 0 0 5.28 0.0000 0

11 Jun 3 157.8 0.0190 42 10 5.28 1.8939 26218 Jun 2 156.7 0.0128 28 4 5.28 0.7576 10524 Jun 0 154.0 0.0000 0 4 5.28 0.7576 105

 3 Jul 1 147.9 0.0068 15 1 5.28 0.1894 26 9 Jul 2 147.5 0.0136 30 1 5.28 0.1894 26

 6 Aug 4 151.7 0.0264 59 5 5.28 0.9470 131 21 Aug 2 149.9 0.0133 30 1 5.28 0.1894 26 2 Sep 4 149.7 0.0267 59 1 5.28 0.1894 26

 9 Oct 1 146.9 0.0068 15 2 5.28 0.3788 52 30 Oct 1 149.5 0.0067 15 0 5.28 0.0000 0

 6 Nov 8 147.4 0.0543 121 1 5.28 0.1894 26 20 Nov 0 147.3 0.0000 0 1 5.28 0.1894 26 27 Nov 0 147.0 0.0000 0 1 5.28 0.1894 26 10 Dec 0 150.2 0.0000 0 0 5.28 0.0000 0 23 Dec 0 153.1 0.0000 0 0 5.28 0.0000 0

21 Jan 0 147.0 0.0000 0 0 5.28 0.0000 028 Jan 0 146.4 0.0000 0 0 5.28 0.0000 0

25 Feb 0 154.7 0.0000 0 0 5.28 0.0000 0

11 Mar 0 147.4 0.0000 0 0 5.28 0.0000 031 Mar 0 146.4 0.0000 0 0 5.28 0.0000 0

16 Apr 1 147.3 0.0068 15 0 5.28 0.0000 023 Apr 0 148.9 0.0000 0 2 5.28 0.3788 52

0.0032

Coastal Region (138.5 km2)

2004

0.0033 0.0033

6.29.9

37.130.5

10.6

6.8

13.1

Table 1. Survey effort and strip-transect estimates of seasonal density by year for turtles on the surface of the Core and Pamlico Sounds, and the coastal region of North Carolina, 2004-06.

0.0103 0.00480.0033 0.0025

1013 5.6

7.3

10.1

0

5285

4

19.3

3.8

26

0

13

0.3788

20052006

Spring

Summer

Autumn

Winter

Spring

Summer

Autumn

Year Season Day

23

7

0.0157 0.0087

7

2535

Sounds (2,221.38 km2) 

0.01150.00000.0017 0.0017

0.0726 0.04450.0947 0.0716

0.2678

0.6155 0.21990.1894 0.04890.00000.0947 0.0947
17

Animals Transects surveyed (km2 ) Density (km2) Estimated turtles Animals Transects surveyed (km2 ) Density (km2) Estimated turtles 

Spring 2005-06 1 538.9 0.0018 2 2 449.2 0.0045 4Summer 2004-05 9 808.4 0.0111 12 12 673.8 0.0178 16Autumn 2004-05 1 875.7 0.0011 1 14 730 0.0192 17Winter 2005-06 0 404.2 0 0 0 336.9 0 0Table 2. Strip-transect estimates of density by season for turtles on the surface of the Western and Eastern Pamlico Sounds, North Carolina, 2004-2006.

Western Pamlico Sound (1,108 km2) Eastern Pamlico Sound (893 km2) 

Season
18

Animals

Transects 

surveyed 

(km2 )

Density 

(km2 )

Mean 

Seasonal 

Density 

Estimate

SE Estimated dolphins

Mean 

Seasonal 

Abundance 

Estimate

SE Animals

Transects 

surveyed 

(km2 )

Density 

(km2 )

Mean 

Seasonal 

Density 

Estimate

SE Estimated dolphins

Mean 

Seasonal 

Abundance 

Estimate

SE

10 Jul 6 167.6 0.0358 80 9 5.76 1.5625 21625 Jul 12 179.6 0.0668 148 1 5.76 0.1736 24

 8 Aug 12 174.4 0.0688 153 0 5.76 0.0000 0 19 Aug 19 167.4 0.1135 252 3 5.28 0.5682 79 27 Aug 5 180.4 0.0277 62 0 5.76 0.0000 0

 4 Sep 0 147.5 0.0000 0 1 5.28 0.1894 26

 3 Oct 22 150.8 0.1459 324 2 5.28 0.3788 52

10 Oct 14 149.6 0.0936 208 2 5.28 0.3788 5224 Oct 63 153.1 0.4115 914 11 5.28 2.0833 28929 Oct 10 145.3 0.0688 153 25 5.28 4.7348 656

 6 Nov 29 145.4 0.1994 443 51 5.28 9.6591 133811 Nov 11 146.7 0.0750 167 13 5.28 2.4621 34120 Nov 81 150.3 0.5389 1197 85 5.28 16.0985 2230

Winter 13 Feb 18 152.2 0.1183 263 105 5.28 19.8864 2754

 6 Mar 7 168.2 0.0416 92 37 5.76 6.4236 890

 14 May 0 158.3 0.0000 0 15 5.28 2.8409 393 22 May 4 152.3 0.0263 58 18 5.28 3.4091 472 30 May 9 152.3 0.0591 131 11 5.28 2.0833 289

 4 Jun 4 151.8 0.0263 59 2 5.28 0.3788 52 11 Jun 15 157.8 0.0951 211 25 5.28 4.7348 656 18 Jun 0 156.7 0.0000 0 2 5.28 0.3788 52 24 Jun 6 154.0 0.0390 87 11 5.28 2.0833 289

 3 Jul 0 147.9 0.0000 0 0 5.28 0.0000 0 9 Jul 2 147.5 0.0136 30 5 5.28 0.9470 131

 6 Aug 1 151.7 0.0066 15 72 5.28 13.6364 1889 21 Aug 2 149.9 0.0133 30 19 5.28 3.5985 498 2 Sep 3 149.7 0.0200 45 23 5.28 4.3561 603

 9 Oct 0 146.9 0.0000 0 0 5.28 0.0000 0 30 Oct 8 149.5 0.0535 119 23 5.28 4.3561 603

 6 Nov 11 147.4 0.0746 166 31 5.28 5.8712 813 20 Nov 4 147.3 0.0272 60 20 5.28 3.7879 525 27 Nov 14 147.0 0.0953 212 14 5.28 2.6515 367

 10 Dec 34 150.2 0.2264 503 43 5.28 8.1439 1128 23 Dec 32 153.1 0.2090 464 124 5.28 23.4848 3253

21 Jan 4 147.0 0.0272 60 8 5.28 1.5152 21028 Jan 0 146.4 0.0000 0 27 5.28 5.1136 708

25 Feb 2 154.7 0.0129 29 35 5.28 6.6288 91811 Mar 12 147.4 0.0814 181 46 5.28 8.7121 120731 Mar 24 146.4 0.1639 364 135 5.28 25.5682 3541

16 Apr 8 147.3 0.0543 121 14 5.28 2.6515 36723 Apr 42 148.9 0.2820 626 7 5.28 1.3258 184

1325 771.7 323 113.6 9.5644 5.5716

2006

Spring 0.1454 0.0512

113.5

Winter 0.0951 0.0503 211 111.8 8.9773 3.7901 1243 524.9

32.6 3.5038 0.8194 485 Autumn 0.0451 0.0147 100

131.7

Summer 0.0242 0.0111 54 24.8 3.2197 1.6031 446 222.0

276.8

2005

Spring 0.0317 0.0125 71 27.8 3.6892 0.9510 511

64 40.8

Autumn 0.1917 0.0663 426 147.3 4.4981 1.9988 623

139 33.6 0.4609 0.2943

2004

Summer 0.0625 0.0151

Table 3. Survey effort and strip-transect estimates of seasonal density by year for dolphins on the surface of the Core and Pamlico Sounds, and the coastal region of North Carolina, 2004-06.

Year Season Day

Sounds (2,221.38 km2) Coastal Region (138.5 km2)
19

Animals Transects surveyed (km2 ) Density (km2) Estimated dolphins Animals Transects surveyed (km2 ) Density (km2) Estimated dolphins 

Spring 2005-06 51 538.94 0.0946 105 51 449.25 0.1135 101Summer 2004-05 30 808.41 0.0371 41 31 673.89 0.0460 41Autumn 2004-05 189 875.78 0.2158 239 37 730.05 0.0506 45Winter 2005-06 11 404.2 0.0272 30 60 336.93 0.1780 159Table 4. Strip-transect estimates of density by season for dolphins on the surface of the Western and Eastern Pamlico Sounds, North Carolina, 2004-2006.

Season

Western Pamlico Sound (1,108 km2) Eastern Pamlico Sound (893 km2) 
20

Date Minimum 

SST (°C) 

Maximum 

SST (°C) 

Mean 

SST (°C)

Standard 

Error of 

Mean SST 

Turtle 

Sightings 

in Sounds

Dolphin 

Sightings 

in Sounds

Turtle 

Sightings 

in coastal 

region

Dolphin 

Sightings in 

coastal 

region

2004

10 Jul 28.64 32.2 29.83 0.14 1 6 0 9

25 Jul 27.08 31.05 29.16 0.32 5 12 0 1

 8 Aug 22.83 29.38 25.88 0.22 0 12 1 0

 19 Aug 25.98 29.55 27.43 0.16 2 19 1 3

 27 Aug 26.02 28.63 27.15 0.08 1 5 0 0

 4 Sep 26.02 28.23 27.2 0.11 0 0 0 1

 3 Oct 23.91 25.64 24.67 0.03 0 22 3 2

10 Oct 21.77 24.43 22.95 0.09 0 14 0 2

24 Oct NA NA NA NA 0 63 0 11

29 Oct 15.92 18.15 16.94 0.06 0 10 1 25

 6 Nov 17.32 19.74 18.31 0.06 0 29 0 51

11 Nov 11.53 15.39 14.08 0.12 1 11 0 13

20 Nov 12.36 13.38 12.69 0.09 3 81 0 85

2005

 13 Feb 6.36 8.99 7.86 0.13 0 18 0 105

 6 Mar 6.87 9.46 7.97 0.14 0 7 0 37

 14 May 19.38 21.08 20.14 0.08 0 0 6 15

 22 May 17.66 18.18 17.88 0.03 0 4 0 18

 30 May NA NA NA NA 2 9 2 11

 4 Jun NA NA NA NA 0 4 0 2

 11 Jun 24.42 25.75 25.18 0.11 3 15 10 25

 18 Jun 26.38 27.12 26.72 0.06 2 0 4 2

 24 Jun 23.74 27.09 25.33 0.13 0 6 4 11

 3 Jul 25.09 27.83 27.09 0.05 1 0 1 0

 9 Jul NA NA NA NA 2 2 1 5

 6 Aug 29.07 32.83 30.82 0.21 4 1 5 72

 21 Aug 27.86 32.49 30.42 0.26 2 2 1 19

 2 Sep 27.17 32.25 29.6 0.21 4 3 1 23

 9 Oct 14.6 16.29 15.53 0.06 1 0 2 0

 30 Oct 24.35 24.85 24.57 0.07 1 8 0 23

 6 Nov 16.98 19.31 17.87 0.06 8 11 1 31

 20 Nov NA NA NA NA 0 4 1 20

 27 Nov 8.71 10.4 9.68 0.10 0 14 1 14

 10 Dec 10.59 10.88 10.78 0.14 0 34 0 43

 23 Dec 5.53 8.49 7.6 0.10 0 32 0 124

2006

21 Jan 8.96 9.66 9.37 0.04 0 4 0 8

28 Jan 10.3 11.83 11.17 0.10 0 0 0 27

25 Feb NA NA NA NA 0 2 0 35

11 Mar 12.68 17.55 14.95 0.13 0 12 0 46

31 Mar 14.03 19.34 15.07 0.12 0 24 0 135

16 Apr 17.67 20.62 19.61 0.09 1 8 0 14

23 Apr 19.72 22.66 21.72 0.09 0 42 2 7

Table 5. Minimum, maximum, and mean sea surface temperature (SST) along aerial survey transects, and 

sea turtles and dolphins sighted in the Core and Pamlico Sounds, and the coastal region of N.C., 2004-06.
21
22
23

Figure 3. Seasonal distribution of turtle sightings from aerial surveys of Core and Pamlico Sounds, and extending one mile offshore, 2004-06. (A). Spring (Mar-May); (B). Summer (June-Aug); (C). Autumn (Sept-Nov); (D). Winter (Dec-Feb). Note: Each symbol

represents one animal. Survey effort was not equal amongst seasons, and therefore the number of sightings shown may reflect differences in effort, not actual abundance.
24

Figure 4. Seasonal distribution of dolphin sightings in aerial surveys of Core and Pamlico Sounds, and extending one mile offshore, 2004-06. (A). Spring (Mar-May); (B). Summer (June-Aug); (C). Autumn (Sept-Nov); (D). Winter (Dec-Feb). Note: Each symbol 

represents one animal. Survey effort was not equal amongst seasons, and therefore the number of sightings shown may reflect differences in effort, not actual abundance.
25

Figure 5. Mean number of turtles sighted at each mean sea surface temperature (SST) during aerial 

surveys of the Core and Pamlico Sounds, NC, 2004-06. Mean SST is the mean SST during a survey. 

Mean Sea Surface Temperature and Turtles Sighted

0

1

2

3

4

5

6

7

5 7 9 11 13 15 17 19 21 23 25 27 29 31

Mean Sea Surface Temperature (°C)

Sighting Rate

Mean Sea Surface Temperature and Turtles Sighted

0

1

2

3

4

5

6

7

5 7 9 11 13 15 17 19 21 23 25 27 29 31

Mean Sea Surface Temperature (°C)

Mean Number of 

Sightings

Mean Sea Surface Temperature and Turtles Sighted

0

1

2

3

4

5

6

7

5 7 9 11 13 15 17 19 21 23 25 27 29 31

Mean Sea Surface Temperature (°C)

Mean Number of Turtles

Mean Sea Surface Temperature and Dolphins Sighted

0

20

40

60

80

100

120

5 7 9 11 13 15 17 19 21 23 25 27 29 31

Mean Sea Surface Temperature (°C)

Mean Number of 

Dolphins

Figure 6. Mean number of dolphins sighted at each mean sea surface temperature (SST) during 

aerial surveys of the Core and Pamlico Sounds, NC, 2004-06. Mean SST is the mean SST during a 

survey. 
26